Warn on using latest documentation (#6418)

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 ## [2.3.0] - 2023-MM-DD
 ### Added
+- Warn on using latest documentation ([#6418](https://github.com/pyg-team/pytorch_geometric/pull/6418))
 - Added basic `pyright` type checker support ([#6415](https://github.com/pyg-team/pytorch_geometric/pull/6415))
 - Added a new external resource for link prediction ([#6396](https://github.com/pyg-team/pytorch_geometric/pull/6396))
 - Added `CaptumExplainer` ([#6383](https://github.com/pyg-team/pytorch_geometric/pull/6383), [#6387](https://github.com/pyg-team/pytorch_geometric/pull/6387))

docs/source/_static/js/version_alert.js

@@ -0,0 +1,19 @@
+function warnOnLatestVersion() {
+  if (!window.READTHEDOCS_DATA || window.READTHEDOCS_DATA.version !== "latest") {
+    return;  // not on ReadTheDocs and not latest.
+  }
+
+  var note = document.createElement('div');
+  note.setAttribute('class', 'admonition note');
+  note.innerHTML = "<p class='first admonition-title'>Note</p> " +
+    "<p> " +
+    "This documentation is for an <b>unreleased development version</b>. " +
+    "Click <a href='/en/stable'><b>here</b></a> to access the documentation of the current stable release." +
+    "</p>";
+
+  var parent = document.querySelector('#pyg-documentation');
+  if (parent)
+    parent.insertBefore(note, parent.querySelector('h1'));
+}
+
+document.addEventListener('DOMContentLoaded', warnOnLatestVersion);

docs/source/conf.py

@@ -49,3 +49,4 @@ def rst_jinja_render(app, _, source):
         source[0] = app.builder.templates.render_string(source[0], rst_context)
 
     app.connect('source-read', rst_jinja_render)
+    app.add_js_file('js/version_alert.js')